相关疑难解决方法(0)

我试图在Angular中实现类似委托模式的东西.当用户点击a时nav-item,我想调用一个函数然后发出一个事件,而该事件又由一些其他组件监听事件来处理.

这是场景:我有一个Navigation组件:

import {Component, Output, EventEmitter} from 'angular2/core';

@Component({
    // other properties left out for brevity
    events : ['navchange'], 
    template:`
      <div class="nav-item" (click)="selectedNavItem(1)"></div>
    `
})

export class Navigation {

    @Output() navchange: EventEmitter<number> = new EventEmitter();

    selectedNavItem(item: number) {
        console.log('selected nav item ' + item);
        this.navchange.emit(item)
    }

}

这是观察组件:

export class ObservingComponent {

  // How do I observe the event ? 
  // <----------Observe/Register Event ?-------->

  public selectedNavItem(item: number) {
    console.log('item index changed!');
  }

}

关键问题是,如何让观察组件观察相关事件？

在AngularJS中,我可以使用ng-model选项去抖模型.

ng-model-options="{ debounce: 1000 }"

如何在Angular中去抖模型？我试图在文档中搜索debounce,但我找不到任何东西.

https://angular.io/search/#stq=debounce&stp=1

一个解决方案是编写我自己的去抖函数,例如:

import {Component, Template, bootstrap} from 'angular2/angular2';

// Annotation section
@Component({
  selector: 'my-app'
})
@Template({
  url: 'app.html'
})
// Component controller
class MyAppComponent {
  constructor() {
    this.firstName = 'Name';
  }

  changed($event, el){
    console.log("changes", this.name, el.value);
    this.name = el.value;
  }

  firstNameChanged($event, first){
    if (this.timeoutId) window.clearTimeout(this.timeoutID);
    this.timeoutID = window.setTimeout(() => {
        this.firstName = first.value;
    }, 250)
  }

}
bootstrap(MyAppComponent);

而我的HTML

<input type=text [value]="firstName" #first (keyup)="firstNameChanged($event, first)">

但是我正在寻找一个内置函数,Angular中有一个吗？

在使用Observables的同时,我正试图围绕最佳实践ChangeDetectionStrategy.OnPush.

该示例演示了想要显示某种加载消息(或者可能是简单的微调器动画)的常见场景:

Plnkr在这里

@Component({
  selector: 'my-app',
  template: `Are we loading?: {{loadingMessage}}`,

  // Obviously "Default" will notice the change in `loadingMessage`...
  // changeDetection: ChangeDetectionStrategy.Default

  // But what is best practice when using OnPush?
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class App implements OnInit {

  private loadingMessage = "Wait for it...";

  constructor() {

  }

  ngOnInit() {

    // Pretend we're loading data from a service.
    // This component is only interested in the call's success
    Observable.of(true)
      .delay(2000)
      .subscribe(success => {

        if(success){
          console.log('Pretend loading: …